SPC AC 181245
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0645 AM CST Tue Jan 18 2022
Valid 181300Z - 191200Z
...NO THUNDERSTORM AREAS FORECAST...
...SUMMARY...
No thunderstorm areas are expected over the conterminous U.S.
...Synopsis/Discussion...
Following the departure of the strong subsynoptic trough from the
Northeast, nearly zonal mid/upper-level flow is expected for most of
the period over the central/eastern CONUS. Positively tilted mean
troughing is expected to develop by the end of the period, over the
north-central through southwestern CONUS. This process will be
related to partial phasing of these northern and southern stream
perturbations, respectively:
1. A strong shortwave trough -- initially evident in moisture-
channel imagery over the northernmost reaches of the Canadian
Prairie Provinces. This feature should move southeastward and
amplify, reaching a position from near James Bay to Lake Superior,
northern MN, ND, and eastern MT, by 12Z tomorrow.
2. A broad, but not particularly strong, perturbation initially
over southern parts of NV/CA and southwestward over Pacific waters
west of northern Baja. This feature should move eastward to the
southern High Plains by 12Z, aiding in low-level warm advection
ahead of the cold front described below.
At the surface, 11Z analysis showed a low over the ND/MB line, near
the International Peace Garden, related to the northern-stream
mid/upper trough. A warm front was drawn southeastward to Lake
Michigan, with a cold front arching across southwestern ND and
southeastern/south-central to northwestern MT. The cyclone should
deepen and move eastward to lake Superior by 00Z, with cold front
reaching southeastern MN, south-central NE and eastern CO. By 12Z,
the cold front should extend across southeastern Lower MI, southern
IL, the Ozarks, southwestern OK, and east-central NM.
A separate, weaker low initially drawn near AMA will move east-
southeastward down the Red River Valley -- ahead of the southern-
stream perturbation -- and should be overtaken by the cold front
within a couple hours of the end of the period. Given the
continental/polar air mass still present over the Gulf and central/
eastern CONUS following the last major cold front, return-flow
marine modification ahead of the newer cold front will be too
limited to yield enough moisture/instability for thunderstorms,
until the day-2 period.
..Edwards/Broyles.. 01/18/2022
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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